1. Field of the Invention
The present invention relates to exhaust conversion systems for completing the combustion of internal combustion engine exhaust gases, more particularly to such exhaust conversion systems further including a mechanism for relieving the back pressure within an exhaust afterburner of the exhaust conversion system.
2. Background Information
It is well-known that the various hydrocarbon fuels employed in internal combustion engines are not completely combusted therein. This unavoidable, incomplete combustion of fuels results in the generation of substantial quantities of unburned or partially burned hydrocarbons, carbon monoxide and other noxious waste gases. These are generally vented to the atmosphere through the exhaust system. Previously, many proposals have been advanced for combatting the pollutional effects caused by such noxious waste gases. Some have attempted to burn or oxidize the exhaust gases by thermal or catalytic conversion techniques. In the catalytic method, the exhaust gases leaving the engine are passed through a conversion unit in which a catalyst is suspended. Such units are rather bulky in construction and difficult to maintain in proper adjustment. Alternatively, in several thermal converting systems, an additional combustion chamber is required in the exhaust system of the engine. These may require additional fuel and an auxiliary ignition system in addition to auxiliary combustion air to accomplish the conversion of exhaust fumes. The use of such secondary fuel, of course, decreases the efficiency of the engine.
U.S. Pat. No. 3,657,878 to John Kaufmann, Jr., who is a joint inventor of the present application, discloses a conversion system for exhaust gases which is mounted in the exhaust of an internal combustion engine. The conversion system of the '878 patent includes a mechanism for inducting auxiliary combustion air directly into the vehicle exhaust system at a point where the heat of the exhaust system is generally sufficient to initiate and to drive the combustion of the exhaust substantially to completion. The difficulty with the prior art system disclosed in the '878 patent is that there is no control of the back pressure within the exhaust afterburner. The buildup of back pressure will decrease operative efficiency of the system. Additionally, the device disclosed in the '878 patent may not provide for sufficient auxiliary air into the afterburner or the ability to control the amount or location of air being input into the afterburner. The present invention overcomes the aforementioned drawbacks of the prior art.